An all-terrain vehicle having a power steering system that is driven according to a signal from a torque sensor is disclosed in Japanese Utility Model Laid-open No. Hei 3-1877. In Japanese Utility Model Laid-open No. Hei 3-1877, a power assist motor and the torque sensor are provided on a steering shaft, and a control unit for controlling the power assist motor and the torque sensor are provided at an upper surface of a rear portion of a vehicle body.
In the conventional configuration as above, when the wiring for connection between the power assist motor or the torque sensor and the control unit becomes long, the possibility that a noise may be contained in the signal from the torque sensor is raised, so that it is necessary to take into account the influence of the noise on the assisting performance. In investigating the layout of the control unit, it is desirable to adopt a configuration in which the capability to protect the control unit from water, mud or the like coming from the road surface can be enhanced while making the wiring short between the control unit and the power assist motor or the torque sensor. In addition, the control unit is present at a load carrying platform at a rear portion of the vehicle body, so that it is also desired to enhance the utility of space.